Homemade, albeit cheap water bag (passive solar heat)

KimHat(7)August 27, 2012

So a kind person on the Greenhouse forum directed me to Farmtek to look at their water walls. These are thick black bags that hold hundreds of gallons of water to help with passive solar heat, which sounds like only really works if you indeed have hundreds of gallons of water. I have not yet built my hoophouse, but am planning it. It think it will be 11.5x 12.5, and covered with 6 mil agricultural plastic and possibly some clear bubble wrap. My question for all of you engineers out there is this: would the new xxl ziploc bags (they hold 20 gallons each) filled with water and sitting in some black garbage bags against one wall work as well as the farmtek water bags? The farmtek water bags for 350 gallons (which is about what I estimate I need for my greenhouse) will run me about $500. The xxl ziplocs (for 18 of them) will run me about $40 and some change. I realize that this will be nowhere near as sturdy as the farmtek bags, but I am hoping if I don't jostle them too much or move them too much, they might last me one season at least. Then I can see how well the passive solar heating will work for me. Anyway, does anyone have any thoughts? Thanks! Kim

There might not be an outlet near you but I suggest govliquidation.com may have something you could use and it could be a lot cheaper.

Another possible to supplement your ziplocs and garbage bags would be to track down some 44-gallon plastic drums. If you are in a dairy farming area, they use various chemicals in quantity for keeping the milking shed hygienic. And the drums have the added advantage of being easily fitted with a pump mechanism or a simple spigot for drawing water. You can also link them to a water capture system from outside and connect them with a siphoning hose so you collect more water for use. (An outlet to an external drain is a good idea.)

One of the first solar homes used storage drums in the basement of the home to store heat for the home. When I worked in the oil-patch those plastic drums were very easy to come across. I think now they try to sell everything people might want so it may take a bit of hunting.